1 Reply Latest reply: Dec 31, 2011 7:45 AM by Strontium90
Raymond Fox Level 2 Level 2 (255 points)

When my Mac's hard drive started to go south, I purchased two 1 TB hard drives to use as my system disc.  Fearing a disc failure, I always purchase hard drives in pairs and then mirror them via a mirrored RAID set.  But this is the first time I've done this for my system disc. 


When attempting to install Lion, the first thing I got was that Lion couldn't install a recovery partition on my disc, which I found out was because it's a RAID setup.  I continued with the installation.  First thing I attempted to do was run Disk Utility to repair any disk permissions which might need fixing (something I do after every update to the system). Come to find that Disk Utility doesn't work on RAID sets under Lion.


Is it a mistake to have my system disk set up as a RAID mirrored set???

3GHz Mac Pro, Mac OS X (10.6.8), 12GB RAM
  • Strontium90 Level 4 Level 4 (3,700 points)

    Something else is amiss.  Disk Utility certaintly works on mirrored RAID sets in Lion.  So you are dealing with something else.


    Now, the loss of the Recovery partition is expected and described here http://support.apple.com/kb/HT4649


    Try using the diskutil command line tool to repair permissions.  Do this by following these steps:


    1:  Open Terminal

    2:  Type the following command followed by hitting return:


         diskutil repairPermissions /


    3:  This will run and complete showing all things that were corrected (or incapable of correcting).


    Once complete, check the health of your RAID set using:


         diskutil checkRAID



    And it is my strong opinion that mirroring a boot volume (especially in a mini) is the best way to mitigate single points of failure.  In most cases, the internal storage of a mini is too small for most deployments.  But the OS, including Open Directory, passwords, etc, will be difficult to rebuild in the event of a disk failure.  Having a mirrored boot is the best way to protect against a drive failure and ensure uptime of the device.


    Of course, we still need to shut the machine off to swap a bad drive, but I digress......